1. Field of the Invention
This invention relates generally to the deployment of inflatable structures, and more particularly to a system and method for deployment of vacuum-packed evacuation slides or life rafts associated with aircraft.
2. Description of the Related Art
Inflatable evacuation slides and/or slide rafts provide a rapid means for evacuating passengers and flight personnel in the event of an emergency. In commercial aircraft, the slides are normally stored uninflated in a container mounted on the interior of the aircraft door or immediately adjacent thereto. With the door closed, a girt bar is connected to brackets on the floor inside the doorway such that it is only necessary to open the door to automatically deploy the slide in the event of an emergency evacuation. When the door is opened, the girt bar normally pulls the slide through the doorway until gravity can take effect to unfold or unroll the slide outside of the doorway. Once outside the doorway, the slide or slide/raft is rapidly inflated through the application of fluid pressure.
In military applications, inflatable life rafts and their inflation systems are sometimes located in wing compartments of the aircraft. This is in order to maximize space in the fuselage for transporting equipment, supplies and personnel. A pair of life rafts and their inflation systems may be located in each wing, and are sometimes stored in a vacuum-sealed package. The vacuum-sealed package reduces the size of the folded life raft and also protects the life raft from water, moisture, fungus growth, jet fuels, exhaust soot and debris. The inflation system for each life raft includes a container of highly pressurized gas with an inflation valve that is actuable from a remote location, such as the cockpit by a cable and pulley system routed through the aircraft. When a pull handle or similar device associated with the cable is activated, the valve is opened and the pressurized gas is discharged from the container and into the life raft causing its rapid inflation. However, during the aircraft maintenance procedures, the cables often having considerable length and pulleys may be painted over and not tested and lubricated for movement on a regular basis. Corrosion and debris can also restrict or resist cable movement. Thus, higher pull forces are required to activate the inflation systems.
The use of vacuum-packed inflatable structures exacerbates this problem since a relatively large amount of force is required to break the vacuum and open the inflation valve, which is typically subject to the vacuum force. Instead of the typical 20 to 30 pounds of pull force required to open the inflation valve, it has been found that prior art solutions require anywhere from 100 to 150 pounds of the pull force due at least in part to the vacuum pressure that must be overcome. This amount of pull force may not only be difficult to generate, but may also affect or damage neighboring mechanisms. In emergency situations, where the inflation system must be actuated, the pilot or other personnel may be injured, lack sufficient strength, or be improperly positioned to apply the necessary pull force.
It would therefore be desirable to provide a system for deploying a life raft or other inflatable structure that substantially reduces the pull force required by an operator or an automatic actuating means to trigger the inflation system.
One aspect of the present invention provides an inflation system for deploying an inflatable structure which includes a primary container fluidly connectable to the inflatable structure. The primary container includes a primary pressurized fluid situated therein and a primary valve movable under a primary applied force from a closed position, while maintaining the primary pressurized fluid in the primary container to an open position while expelling the primary pressurized fluid into the inflatable structure for its inflation. The inflation system further includes an inflatable actuator bag and a secondary container fluidly connectable to the inflatable actuator bag. The secondary container has a secondary pressurized fluid located therein and a secondary valve movable under a secondary applied force from a closed position while maintaining the secondary pressurized fluid in the secondary container to an open position while expelling the secondary pressurized fluid into the inflatable actuator bag. With this arrangement, application of the secondary force to the secondary valve causes the secondary fluid to inflate the inflatable actuator bag and open the first valve with at least the primary applied force, to thereby inflate the inflatable structure. Preferably, the secondary force is greater than the primary force.
Another aspect of the invention provides an inflatable structure in combination with an inflation system for deploying the inflatable structure which includes an envelope containing the inflatable structure under vacuum pressure. A primary container is fluidly connectable to the inflatable structure. The primary container has a primary pressurized fluid located therein and a primary valve movable under a primary applied force from a closed position while maintaining the primary pressurized fluid in the primary container to an open position while expelling the primary pressurized fluid into the inflatable structure to thereby inflate the inflatable structure. The primary valve is also subject to the vacuum pressure in the envelope. An inflatable actuator bag is connected to the envelope and is also subject to the vacuum pressure in the envelope. A first connecting arrangement extends between the envelope and the inflatable actuator bag. A distal end of the first connecting arrangement is connected to the primary valve for moving the primary valve to the open position and a proximal end of the first connecting arrangement is connected to a wall of the inflatable actuator bag. A secondary container is fluidly connectable to the inflatable actuator bag. The secondary container has a second pressurized fluid located therein and a secondary valve movable under a secondary applied force from a closed position while maintaining the secondary pressurized fluid in the secondary container to an open position while expelling the secondary pressurized fluid into the inflatable actuator bag. With this arrangement, application of the secondary force to the secondary valve causes the secondary fluid to inflate the inflatable actuator bag, thereby overcoming the vacuum force and causing the first connecting arrangement to open the primary valve with at least the primary force and inflate the inflatable structure. Preferably, the secondary force is greater than the primary force.